U.S. Pat. No. 3,920,822 discloses pharmacologically active cyanoguanidines of the formula ##STR1## wherein R is H or lower alkyl, X is H, lower alkyl, --CF.sub.3, --OH, halogen or amino, Z is --S-- or --O--, m is 0, 1 or 2 and n is 2 or 3, the sum of m and n being 3 or 4.
Diuretic halopyrazinoyl guanidines of the formula ##STR2## ARE DISCLOSED IN U.S. Pat. No. 3,313,813.
No examples of N-heterocyclic guanidines more closely resembling the compounds of the present invention have been found in the literature.